nanog mailing list archives

Re: Forwarding issues related to MACs starting with a 4 or a 6 (Was: [c-nsp] Wierd MPLS/VPLS issue)


From: Christopher Morrow <morrowc.lists () gmail com>
Date: Fri, 2 Dec 2016 11:07:43 -0500

On Fri, Dec 2, 2016 at 11:02 AM, Simon Lockhart <simon () slimey org> wrote:

On Fri Dec 02, 2016 at 10:29:56AM -0500, Christopher Morrow wrote:
you'd think standard testing of traffic through the asic path somewhere
between 'let's design an asic!' and 'here's your board ms customer!'
would
have found this sort of thing, no? or does testing only use 1 mac address
ever?

Well, it's actually payload, rather than src/dst MAC used for forwarding,
so
there's quite a few more combinations to look for...

2^(8*9216) is quite a lot of different packets to test through the
forwarding
path... But, wait, that assumes every bit combination for 9216 byte
packets,
but the packet might be shorter than that... So multiply that by (9216-64).


but  most/all forwarding asics (aside from perhaps extreme's?) only deal
with the first N bits in the header (128 or so..) so... not quite as many
right?


Anyone want to work out how many years that'd take to test, even at 100G?

Simon



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